I could not find the below paper in PubMed, but it sure gave me the sense that messing with mouse thermoregulation is not a good model of the human condition. We do not get torpor.
I too will chose comfort.
"BAT weight also increased in mice exposed to
extremely warm temperatures of 35 and 37.5 degrees C, environments
that are well above the limits of normothermy for mice and must
have certainly been stressful.'
Journal of Thermal Biology Volume 37, Issue 8, December 2012, Pages 654–685
Thermal physiology of laboratory mice: Defining thermoneutrality
In terms of total number of publications, the laboratory mouse (Mus musculus) has emerged as the most popular test subject in biomedical research. Mice are used as models to study obesity, diabetes, CNS diseases and variety of other pathologies. Mice are classified as homeotherms and regulate their core temperature over a relatively wide range of ambient temperatures. However, researchers find that the thermoregulatory system of mice is easily affected by drugs, chemicals, and a variety of pathological conditions, effects that can be exacerbated by changes in ambient temperature. To this end, a thorough review of the thermal physiology of mice, including their sensitivity and regulatory limits to changes in ambient temperature is the primary focus of this review. Specifically, the zone of thermoneutrality for metabolic rate and how it corresponds to that for growth, reproduction, development, thermal comfort, and many other variables is covered. A key point of the review is to show that behavioral thermoregulation of mice is geared to minimize energy expenditure. Their zone of thermal comfort is essentially wedged between the thresholds to increase heat production and heat loss; however, this zone is above the recommended guidelines for animal vivariums. Future work is needed to better understand the behavioral and autonomic thermoregulatory responses of this most popular test species.
Laboratory mice have become the predominant test species in most disciplines of biomedicine.
Mice are housed at temperatures that subject them to moderate cold stress.
Their temperature and metabolisms stability is susceptible to a variety of drugs and pathological conditions.
This review focuses on the thermoneutral zone of laboratory mice.
The impact of temperature on growth, reproduction, organ development, and behavior is explored in detail.
Ambient temperature; Metabolic rate; Evaporative water loss; Core temperature; Telemetry; Selected temperature; Huddling; Brown adipose tissue; Thermal conductance; Growth; Reproduction; Fever; Aging
(Koizumi etal.,1992; Swoap andGutilla,2009; Solymar etal.,
siveness tostimuli.Duringtorpormicedisplayastateof heterothermy,
or deprivation(forreview, Gordon, 1990), thecoretemperatureof
perature of19 1C isshown(Fig. 16A andB).Onecansee
rate after 6 hoffooddeprivation.Metabolicrateandheartrate
recover spontaneouslyafter 16 hinspiteofthecontinuation
of fooddeprivation(fordetails,see Swoap andGutilla,2009).
when theyarefastedat23 1C (Williams etal.,2002). Core
temperature offooddeprivedmicemaintainedat28 1C falls
to 341 after thefirstdayoffasting,recovers,andthenfallagain
to 29 1C aftertheseconddayoffasting(Kanizsai etal.,2009).
food isunavailable(see Fig. 16A). Thispatternappearstobe
ning tobeunderstood(Swoap andGutilla,2009).
(Turturro etal.,1999; Speakman andMitchell,2011). Theanti-
ment. Koizumi etal.(1992) monitored coretemperatureby
tained bodyweightat20gcomparedto 40 gincontrolanimals.
reduced dramaticallybythistreatment(Fig. 17A). Forexample,
control micemaintaintheircoretemperaturebetween35–39 1C,
temperature inthis35–39 1C rangeforonly12h/dayandarange
of 23–27 1C for3–6h/day.Inastudyfromthesamelaboratory,
6 montholdmicethathadbeenrearedonadietthatwas 60%
of thedarkphaseandrecoveredslowlyduringtheday(Fig. 17B).
of 30 1C althoughthemitoticindexhadnotcompletelyrecovered
by thisthermoneutraltreatment(Koizumi etal.,1992).
tions ofvivariumlistedin Table 2). Alltogether,anymeasurement
by Herrington (1940) utilized micethatwerefooddeprivedforup
7.1. Brown adipose tissue
that isakintoathermoneutralzone(Fig. 27). Albinoand
30 1C. Interestingly,BATweightalsoincreasedinmiceexposedto
extremely warmtemperaturesof35and37.5 1C, environments
temperatures of21 1C andgreater.Morerecently, Zhao etal.
(2010) found aneardoublingintheweightofBATinmaleSwiss
sure temperaturewasreducedfrom23to15to8toO 1C intwo
serum T3 levels andreductionsin T4."
"11.1. Conclusion: Mice are unique thermoregulators
Thermal physiologists strive to study the many facets of
thermoregulation of species with a rich variety of morphological
adaptations. Volumes have been written about animals with
unique thermoregulatory characteristics, such as arctic and tropical
mammals that have remarkable tolerances to extremely
high or low ambient or body temperatures. Likewise, evolution,
natural history, and selective breeding are all attributes that make
the mouse a unique thermoregulator. Researchers that use mice
as a human surrogate are certainly aware of the many caveats
that limit extrapolation from mouse to human. Mice are not
miniaturized versions of rats or humans in terms of their
thermoregulatory system despite the fact that their average core
temperatures differ by just 1 1C. We should consider the mouse as
a unique thermoregulator with its small size, narrow thermoneutral
zone, preference for comparatively warm ambient temperatures,
and ability to allow core temperature to vary widely
in some environments or regulate in others. This is especially true
in the use of mice and other rodents to study human metabolic
syndrome, as discussed in recent excellent reviews by Overton
(2010) and Cannon and Nedergaard ( 2011). In view of the recent
growth in the use of mice as test organism for most biomedical
disciplines, we need to have a better understanding of their
Edited by AlPater, 07 March 2016 - 05:31 PM.